Platts taught in Georgia before starting with the U.S. Department of Agriculture (USDA) in Selma as the home demonstration agent for Dallas County. She educated the county's largely rural population about food production and processing, nutrition, healthcare, and other subjects related to agriculture and homemaking.[4][7]

She met her future husband Samuel William Boynton in Selma, where he was working as a county extension agent during the Great Depression. They married in 1936[4] and had two sons, Bill Jr. and Bruce Carver Boynton. Her son, Bruce Carver Boynton, was the godson and namesake of George Washington Carver.[8] Later they adopted Amelia's two nieces Sharon (Platts) Seay and Germaine (Platts) Bowser.[3] Amelia and Samuel had known the noted scholar George Washington Carver at the Tuskegee Institute, from which they both graduated.[9]

In 1958, her son, Bruce Boynton, was a student at Howard University School of Law when he was arrested while attempting to purchase food at the white section of a bus terminal in Richmond, Virginia. Arrested for trespassing, Bruce Boynton was found guilty in state court of a misdemeanor and fined, which he appealed and lost until the case, Boynton v. Virginia, was argued before the U.S. Supreme Court by Thurgood Marshall, reversing lower court decisions.[3][5]

In 1963, Samuel Boynton died. It was a time of increased activism in the Civil Rights Movement. Amelia made her home and office in Selma a center for strategy sessions for Selma's civil rights battles, including its voting rights campaign. In 1964 Boynton ran for the Congress from Alabama, hoping to encourage black registration and voting. She was the first female African American to run for office in Alabama and the first woman of any race to run for the ticket of the Democratic Party in the state. She received 10% of the vote.[3][7]

To protest continuing segregation and disenfranchisement of blacks, in early 1965 Amelia Boynton helped organize a march to the state capital of Montgomery, initiated by James Bevel, which took place on March 7, 1965. Led by John Lewis, Hosea Williams and Bob Mants, and including Rosa Parks and others among the marchers,[11] the event became known as Bloody Sunday when county and state police stopped the march and beat demonstrators after they crossed the Edmund Pettus Bridge into Dallas County.[11] Boynton was beaten unconscious; a photograph of her lying on Edmund Pettus Bridge went around the world.[13][14]

Then they charged. They came from the right. They came from the left. One [of the troopers] shouted: 'Run!' I thought, 'Why should I be running?' Then an officer on horseback hit me across the back of the shoulders and, for a second time, on the back of the neck. I lost consciousness.

Boynton suffered throat burns from the effects of tear gas.[14] She participated in both of the subsequent marches. Another short march led by Martin Luther King took place two days later; the marchers turned back after crossing the Pettus Bridge. Finally, with federal protection and thousands of marchers joining them, a third march reached Montgomery on March 24, entering with 25,000 people.[11]

The events of Bloody Sunday and the later march on Montgomery galvanized national public opinion and contributed to the passage of the Voting Rights Act of 1965; Boynton was a guest of honor at the ceremony when President Lyndon Johnson signed the Voting Rights Act into law in August of that year.[4][5][15][16]

Boynton remarried in 1969, to a musician named Bob W. Billups. He died unexpectedly in a boating accident in 1973.[3][6] Amelia Boynton eventually married a third time, to former Tuskegee classmate James Robinson in 1976.[3] She moved with him to his home in Tuskegee after the wedding.[17] James Robinson died in 1988.[6]

In 1983, Robinson met Lyndon LaRouche, considered a highly controversial political figure in the Democratic Party. A year later she served as a founding board member of the LaRouche-affiliated Schiller Institute.[18] LaRouche was later convicted in 1988 of mail fraud involving twelve counts, over a ten-year period, totaling $280,000.[19] In 1991, the Schiller Institute published a biography of Robinson, who even into her 90s was described as "LaRouche's most high-profile Black spokeswoman."[20][21]

In 1992, proclamations of "Amelia Boynton Robinson Day" in Seattle and in the state of Washington were rescinded when officials learned of Robinson's involvement in the Schiller Institute. It was the first time the state had pulled back such an honor.[2] A spokesman for the Seattle mayor said,

It was a very difficult decision. The mayor has a lot of respect for her courage during the Civil Rights Movement of the 1960s, but we don't feel her handlers gave us full and accurate information about her current activities.[2]

Robinson said in an interview,

I have had worse things than that done to me when I was fighting for people's right to vote. I have been called rabble-rouser, agitator. But because of my fighting, I was able to hand to the entire country the right for people to vote. To give me an honor and rescind it because I am fighting for justice and for a man who has an economic program that will help the poor and the oppressed ... if that is the reason, then I think they did more good than they did harm.[2]

According to the Associated Press, she said that people get the wrong image of LaRouche because government leaders are spreading lies about him."[2]

In 2004 Robinson sued The Walt Disney Company for defamation, asking for between $1 and $10 million in damages. She contended that the 1999 TV movie Selma, Lord, Selma, a docudrama based on a book written by two young participants in Bloody Sunday, falsely depicted her as a stereotypical "black Mammy," whose key role was to "make religious utterances and to participate in singing spirituals and protest songs." She lost the case.[4][22]

In 1990, Boynton (by then remarried and using the surname of Robinson) was awarded the Martin Luther King, Jr. Freedom Medal.[2] Her memoir, Bridge Across Jordan, includes tributes from friends and colleagues, including Coretta Scott King and Andrew Young.

In Bridge Across Jordan, Amelia Boynton Robinson has crafted an inspiring, eloquent memoir of her more than five decades on the front lines of the struggle for racial equality and social justice. This work is an important contribution to the history of the black freedom struggle, and I wholeheartedly recommend it to everyone who cares about human rights in America.[27]

In 2014, the Selma City Council renamed five blocks of Lapsley Street as Boyntons Street to honor Amelia Boynton Robinson and Sam Boynton.[28]

Robinson is played by Lorraine Toussaint in the 2014 film Selma, about the Selma Voting Rights Movement and its Selma to Montgomery marches. Robinson, then 103 years old, was unable to travel to see the film. Paramount Pictures set up a private screening in her home to include her friends and family. A CNN reporter was present to discuss the film and her experiences at Selma, and she said she felt the film was fantastic.[29]